1. Field of the Invention
The invention proceeds from a measuring device for a metal-enclosed, gas-insulated high-voltage installation. Such a measuring device contains at least one sensor arranged in an enclosure tube, filled with insulating gas, of the metal enclosure, and an electronic evaluation device processing output signals on the at least one sensor. The measuring device serves principally to measure a current conducted in an inner conductor of the high-voltage installation, and/or to measure the voltage of this inner conductor, but can also be used to measure other physical quantities of the installation, for example to measure the pressure, the temperature and/or the density of the insulating gas, or to measure partial discharges.
2. Discussion of Background
The invention refers in this connection to a prior art of measuring devices for metal-enclosed, gas-insulated high-voltage installations such as is disclosed, for example, in EP 0 510 311 A2. The combined current and voltage transformer for a metal-enclosed, gas-insulated high-voltage installation described in this prior art contains in the interior of an enclosure tube, filled with insulating gas, of the metal enclosure a Rogovski coil, which is led around a current-carrying conductor, and serves to measure the conductor current, as well as a tubular metal electrode, which is arranged concentrically with the conductor in an electrically isolated fashion and serves to measure the conductor voltage. Output signals emitted by the Rogovski coil and the measuring electrode are led in shielded lines through the wall of the enclosure tube to an evaluation electronics system, which is situated remote from the metal enclosure and in which there are formed from the output signals measured values which correspond to the current conducted in the conductor or to the voltage present across the conductor. However, it is not possible in this case reliably to exclude environmentally induced variations or disturbances in the output signals, for example as a consequence of the electromagnetic fields or of the effect of mechanical forces on the transmission lines.